1. Field of the Invention
The present invention relates to spin valve thin-film magnetic devices, thin-film magnetic heads, and floating type magnetic heads, and to methods for manufacturing spin valve thin-film magnetic devices, and more particularly, relates to a spin valve thin-film magnetic device in which the asymmetry thereof can be reduced.
2. Description of the Related Art
A giant magnetoresistive head is provided with a device having magnetoresistance, in which the device has a multilayer structure composed of a plurality of materials exhibiting giant magnetoresistance. Among several types of structures exhibiting giant magnetoresistance, a spin valve thin-film magnetic device may be mentioned as a device which has a relatively simple structure and a high rate of change in resistance with respect to application of a minute external magnetic field. As a spin valve thin-film magnetic device, a single spin valve thin-film magnetic device and a dual spin valve thin-film magnetic device may be mentioned.
FIGS. 28 and 29 show schematic cross-sectional views of conventional spin valve thin-film magnetic devices. FIG. 28 is a cross-sectional view observed from a recording medium side, and FIG. 29 is a cross-sectional view observed from a track width direction side.
In FIGS. 28 and 29, an X1 direction in the figure is the track width direction of the spin valve thin-film magnetic device, a Y direction in the figure is the direction of a leakage magnetic field from the magnetic recording medium, and a Z direction in the figure is the moving direction of the magnetic recording medium.
The spin valve thin-film magnetic device 9 shown in FIGS. 28 and 29 is a so-called a dual spin valve thin-film magnetic device composed of a free magnetic layer provided on each surface thereof in the thickness direction with a nonmagnetic conductive layer, a fixed magnetic layer, and an antiferromagnetic layer, in that order, from the free magnetic layer.
In the spin valve thin-film magnetic device 9, an underlying layer 115 is formed on an insulating layer 264, and on the underlying layer 115, a second antiferromagnetic layer 172, a second fixed magnetic layer 151, a second nonmagnetic conductive layer 132, a free magnetic layer 141, a first nonmagnetic conductive layer 131, a first fixed magnetic layer 121, a first antiferromagnetic layer 171, and a cap layer 114 are sequentially formed, in that order.
In addition, on both sides of a laminate composed of the layers from the underlying layer 115 to the cap layer 114 in the X1 direction in the figure, conductive layers 116 and 116, interlayers 117 and 117, bias layers 118 and 118, and bias underlying layers 119 and 119 are formed.
The first and the second fixed magnetic layers 121 and 151 are magnetized respectively by exchange anisotropic magnetic fields which appear at the interfaces between the first fixed magnetic layers 121 and the first antiferromagnetic layers 171 and between the second fixed magnetic layer 151 and the second antiferromagnetic layer 172, and the magnetization directions of the first and the second fixed magnetic layers 121 and 151 are fixed in the Y direction in the figure.
The free magnetic layer 141 is placed in a single domain state by the bias layers 118 and 118, and the magnetization direction of the free magnetic layer 141 is aligned in the direction opposite to the X1 direction in the figure, i.e., in the direction crossing the magnetization directions of the first and the second fixed magnetic layers 121 and 151.
When the free magnetic layer 141 is placed in a single domain state, the generation of Barkhausen noise is prevented.
In this spin valve thin-film magnetic device 9, when sensing current is imparted from the conductive layers 116 and 116 to the free magnetic layer 141, the first and the second nonmagnetic conductive layers 131 and 132, and the first and the second fixed magnetic layers 121 and 151, and when leakage magnetic field from the magnetic recording medium running to the Z direction is imparted to the free magnetic layer 141 in the Y direction in the figure, the magnetization direction of the free magnetic layer 141 is changed from the direction opposite to the X1 direction to the Y direction. The combination of the change in the magnetization direction in the free magnetic layer 141 and the magnetization directions of the first and the second fixed magnetic layers 121 and 151 changes the electrical resistance, and the leakage magnetic field from the recording medium is detected by the change in voltage in accordance with the change in the electrical resistance.
In a typical spin valve thin-film magnetic device, as shown in FIG. 30, when an external magnetic field from the recording medium is not applied, it is ideal for the magnetization direction H3 of the free magnetic layer 141 to be perpendicular to the magnetic directions H1 and H2 of the first and the second fixed magnetic layers 121 and 151.
However, in the conventional spin valve thin-film magnetic device 9, ferromagnetic interlayer coupling occurs between the free magnetic layer 141 and the first and the second fixed magnetic layers 121 and 151 with the first and the second nonmagnetic conductive layers 131 and 132, respectively, and as a result, magnetic moments H4 and H5 are generated by the ferromagnetic interlayer coupling magnetic fields. The directions of the magnetic moments H4 and H5 are parallel to the magnetization directions of the first and the second fixed magnetic layers 121 and 151, i.e., the directions of the magnetic moments H4 and H5 are in the Y direction in the figure.
Consequently, since the magnetization direction H3 of the free magnetic layer 141 is inclined by the magnetic field moments H4 and H5 to the Y direction so as to be H6, and hence, the magnetization direction H6 of the free magnetic layer 141 cannot be perpendicular to the magnetization directions H1 and H2 of the first and the second fixed magnetic layers 121 and 151, there is a problem in that an asymmetric property (hereinafter referred to as xe2x80x9casymmetryxe2x80x9d) of wave shapes for reading is increased.
In addition, in the conventional spin valve thin-film magnetic device 9, as shown in FIG. 31, when an external magnetic field from the recording medium is not applied, it is ideal for the magnetization direction H3 of the free magnetic layer 141 to be perpendicular to the magnetic directions H1 and H2 of the first and the second fixed magnetic layers 121 and 151. However, dipole magnetic fields H14 and H15 leaked from the first and the second fixed magnetic layers 121 and 151, respectively, penetrate into the free magnetic layer 141 from the direction opposite to the Y direction in the figure and incline the magnetization direction H3 of the free magnetic layer 141 toward the magnetization direction H16 which is a direction opposite to the Y direction. As a result, the magnetization direction H16 of the free magnetic layer 141 cannot be perpendicular to the magnetization directions H1 and H2 of the first and the second fixed magnetic layers 121 and 151, and there is a problem in that the asymmetry wave shapes for reading, i.e., the asymmetry, is increased.
In consideration of the problems described above, an object of the present invention is to provides a spin valve thin-film magnetic device in which the inclination of the magnetization direction of the free magnetic layer can be prevented, and the asymmetry can be reduced, a thin-film magnetic head provided with the spin valve thin-film magnetic device, and a floating type magnetic head provided with the thin-film magnetic head. The present invention also provides a method for manufacturing the spin valve thin-film magnetic device described above.
To these ends, the structures described below are employed in the present invention.
A spin valve thin-film magnetic device according to the present invention, comprises a free magnetic layer, a pair of nonmagnetic conductive layers formed on both sides of the free magnetic layer in the thickness direction thereof, a pair of fixed magnetic layers formed on the pair of nonconductive layers, a pair of antiferromagnetic layers formed on the pair of fixed magnetic layers, a pair of conductive layers imparting a sensing current to the free magnetic layer, the pair of nonmagnetic conductive layers, and the pair of fixed magnetic layers, and a pair of bias layers for aligning a magnetization direction of the free magnetic layer, wherein the free magnetic layer is a laminate composed of at least 2L ferromagnetic layers with a nonmagnetic interlayer provided therebetween, the L being an integer of 1 or more, in which magnetization directions of the ferromagnetic layers adjacent to each other are antiparallel to each other so that the entire free magnetic layer is in a ferrimagnetic state; one of the pair of the fixed magnetic layers is a laminate composed of at least 2M ferromagnetic layers with a nonmagnetic layer provided therebetween, the M being an integer of 1 or more, in which magnetization directions of the ferromagnetic layers adjacent to each other are antiparallel to each other so that the entire fixed magnetic layer is in a ferrimagnetic state, and a magnetization direction of the entire fixed magnetic layer is fixed in a direction crossing the magnetization direction of the entire free magnetic layer by an exchange coupling magnetic field formed by the fixed magnetic layer and one of the antiferromagnetic layers adjacent thereto; the other fixed magnetic layer is a laminate composed of at least 2N ferromagnetic layers with a nonmagnetic layer provided therebetween, the N being an integer of 1 or more, in which magnetization-directions of the ferromagnetic layers adjacent to each other are antiparallel to each other so that the entire other fixed magnetic layer is in a ferrimagnetic state, and a magnetization direction of the entire other fixed magnetic layer is fixed in a direction parallel to the magnetization direction of the fixed magnetic layer by an exchange coupling magnetic field formed by the other fixed magnetic layer and the other antiferromagnetic layer adjacent thereto; and a magnetization direction of a ferromagnetic layer, which is closest to the free magnetic layer among the ferromagnetic layers forming the fixed magnetic layer, and a magnetization direction of a ferromagnetic layer, which is closest to the free magnetic layer among the ferromagnetic layers forming the other fixed magnetic layer, are antiparallel to each other.
According to the spin valve thin-film magnetic device described above, the fixed magnetic layer is composed of the even number 2L of ferromagnetic layers, and the other fixed magnetic layer is composed of the even number 2N of ferromagnetic layers, in which, when magnetization directions of these fixed magnetic layers are parallel to each other, magnetization directions of ferromagnetic layers, which are closest to the free magnetic layer among ferromagnetic layers forming individual fixed magnetic layers, are simultaneously antiparallel to each other. Consequently, the magnetization direction of the free magnetic layer can be aligned in the direction perpendicular to the magnetization directions of these fixed magnetic layers.
The magnetization direction of the free magnetic layer can generally be aligned in one direction by the bias layers. However, the magnetization direction of the free magnetic layer provided between the fixed magnetic layers may be inclined depending on the magnetizations thereof, and as a result, the asymmetry may not be reduced in some cases.
However, according to the spin valve thin-film magnetic device described above, the magnetization direction of the free magnetic layer is unlikely to be influenced by the magnetizations of the fixed magnetic layers, and hence, the asymmetry can be reduced.
In the spin valve thin-film magnetic device of the present invention described above, the direction of a magnetic field moment Hb1 of a ferromagnetic exchange coupling magnetic field formed by ferromagnetic interlayer coupling of the free magnetic layer and a ferromagnetic layer, which is closest to the free magnetic layer among the ferromagnetic layers forming the fixed magnetic layer, and the direction of a magnetic field moment Hb2 of a ferromagnetic exchange coupling magnetic field formed by ferromagnetic interlayer coupling of the free magnetic layer and a ferromagnetic layer, which is closest to the free magnetic layer among the ferromagnetic layers forming the other fixed magnetic layer, are antiparallel to each other in the free magnetic layer.
According to the spin valve thin-film magnetic device described above, since the directions of the magnetic moments Hb1 and Hb2 of the ferromagnetic interlayer coupling magnetic fields formed by the free magnetic layer and the individual ferromagnetic layers, which are closest to the free magnetic layer among the ferromagnetic layers forming the fixed magnetic layer and the other fixed magnetic layer, are antiparallel to each other in the free magnetic layer, the ferromagnetic interlayer coupling magnetic fields counteract each other, and hence, the magnetization direction of the free magnetic layer is not inclined by the ferromagnetic interlayer coupling magnetic fields. As a result, the magnetization direction of the free magnetic layer can be aligned in the direction perpendicular to those of the fixed magnetic layers, and hence, the asymmetry of the spin valve thin-film magnetic device can be reduced.
In the spin valve thin-film magnetic device according to the present invention, it is preferable that the L be 1, the M be 1, and the N be 1.
When the spin valve thin-film magnetic device has the structure as described above, the thicknesses of the free magnetic layer and the fixed magnetic layers are decreased, and shunting of the sensing current can be prevented, whereby the rate of change in magnetoresistance can be increased.
In the spin valve thin-film magnetic device according to the present invention, it is preferable that one of the fixed magnetic layers described above be composed of a first ferromagnetic layer and a second ferromagnetic layer with a first nonmagnetic layer provided therebetween, in which the thickness of the second ferromagnetic layer formed at a location closer to the free magnetic layer is larger than that of the first ferromagnetic layer, and that the other fixed magnetic layer be composed of a third ferromagnetic layer and a fourth ferromagnetic layer with a second nonmagnetic layer provided therebetween, in which the thickness of the third ferromagnetic layer formed at a location closer to the free magnetic layer is smaller than that of the fourth ferromagnetic layer.
In addition, in the spin valve thin-film magnetic device according to the present invention, one of the fixed magnetic layers described above may be composed of a first ferromagnetic layer and a second ferromagnetic layer with a first nonmagnetic layer provided therebetween, in which the thickness of the second ferromagnetic layer formed at a location closer to the free magnetic layer is smaller than that of the first ferromagnetic layer, and that the other fixed magnetic layer may be composed of a third ferromagnetic layer and a fourth ferromagnetic layer with a second nonmagnetic layer provided therebetween, in which the thickness of the third ferromagnetic layer disposed at a location closer to the free magnetic layer is larger than that of the fourth ferromagnetic layer.
A thin-film magnetic head of the present invention is capable of reading magnetically written information, which comprises one of the spin valve thin-film magnetic devices described above.
A floating type magnetic head of the present invention comprises a slider and the thin-film magnetic head described above provided in the slider.
Since the thin-film magnetic head and the floating type magnetic head comprise the spin valve thin-film magnetic devices in which the asymmetry thereof is reduced, a superior symmetric property of wave shapes for reading can be obtained, and the rate of occurrence of errors in reading can be reduce.
A method for manufacturing a spin valve thin-film magnetic device of the present invention, comprises a step of forming an antiferromagnetic layer, a fixed magnetic layer composed of at least 2M ferromagnetic layers coupled antiferromagnetically with each other with a nonmagnetic layer provided therebetween, in which the M is an integer of 1 or more, a nonmagnetic conductive layer, a free magnetic layer composed of at least 2L ferromagnetic layers coupled antiferromagnetically with each other with a nonmagnetic interlayer provided therebetween, in which the L is an integer of 1 or more, the other nonmagnetic conductive layer, the other fixed magnetic layer composed of at least 2N ferromagnetic layers coupled antiferromagnetically with each other with a nonmagnetic layer provided therebetween, in which the N is an integer of 1 or more, and the other antiferromagnetic layer so as to form a laminate; and a step of performing a heat treatment for the laminate, while an external magnetic field is applied to the laminate, which is smaller than a magnetic field at which spin flop transformations occur in the ferromagnetic layers forming the fixed magnetic layer and the other fixed magnetic layer, whereby exchange coupling magnetic fields appear between the antiferromagnetic layer and the fixed magnetic layer and between the other antiferromagnetic layer and the other fixed magnetic layer.
The external magnetic field is preferably 8.0xc3x97104 A/m or less.
According to the method for manufacturing a spin valve thin-film magnetic device described above, by the step of forming the laminate composed of the free magnetic layer, the fixed magnetic layers, the nonmagnetic conductive layers, and the antiferromagnetic layers, as described above, followed by the step of performing the heat treatment while the external magnetic field is applied which is smaller than that at which spin flop transformations occur in the individual ferromagnetic layers forming the fixed magnetic layers, a spin valve thin-film magnetic device as described above can be easily manufactured.
In addition, in order to solve the conventional problems described above, the structures described below are employed in the present invention.
A spin valve thin-film magnetic device according to the present invention, comprises a free magnetic layer, a pair of nonmagnetic conductive layers formed on both sides of the free magnetic layer in the thickness direction thereof, a pair of fixed magnetic layers formed on the pair of nonconductive layers, a pair of antiferromagnetic layers formed on the pair of fixed magnetic layers, a pair of conductive layers imparting a sensing current to the free magnetic layer, the pair of nonmagnetic conductive layers, and the pair of fixed magnetic layers, and a pair of bias layers for aligning a magnetization direction of the free magnetic layer, wherein the free magnetic layer is a laminate composed of at least 2L ferromagnetic layers with a nonmagnetic interlayer provided therebetween, the L being an integer of 1 or more, in which magnetization directions of the ferromagnetic layers adjacent to each other are antiparallel to each other so that the entire free magnetic layer is in a ferrimagnetic state; one of the pair of fixed magnetic layers is a laminate composed of at least 2M ferromagnetic layers with a nonmagnetic layer provided therebetween, the M being an integer of 1 or more, in which magnetization directions of the ferromagnetic layers adjacent to each other are antiparallel to each other so that the entire fixed magnetic layer is in a ferrimagnetic state, and a magnetization direction of the entire fixed magnetic layer is fixed in a direction crossing the magnetization direction of the entire free magnetic layer by an exchange coupling magnetic field formed by the fixed magnetic layer and one of the antiferromagnetic layer adjacent thereto; the other fixed magnetic layer is one of a single ferromagnetic layer and a laminate composed of at least 2N+1 ferromagnetic layers with a nonmagnetic layer provided therebetween, the N being an integer of 1 or more, magnetization directions of the ferromagnetic layers adjacent to each other being antiparallel to each other so that the entire other fixed magnetic layer is in a ferrimagnetic state, and a magnetization direction of the entire other fixed magnetic layer is fixed so as to be antiparallel to the magnetization direction of the fixed magnetic layer by an exchange coupling magnetic field formed by the other fixed magnetic layer and the other antiferromagnetic layer adjacent thereto; and a magnetization direction of a ferromagnetic layer, which is closest to the free magnetic layer among the ferromagnetic layers forming the fixed magnetic layer, and a magnetization direction of a ferromagnetic layer, which is closest to the free magnetic layer among the ferromagnetic layers forming the other fixed magnetic layer, are antiparallel to each other.
According to the thin-film magnetic device described above, the fixed magnetic layer is composed of 2L ferromagnetic layers, i.e., an even number of ferromagnetic layers, and the other fixed magnetic layer is composed of a single ferromagnetic layer or 2N+1 ferromagnetic layers, i.e., an odd number of ferromagnetic layers, in which, when the magnetization directions of these fixed magnetic layers are antiparallel to each other, magnetization directions of ferromagnetic layers, which are closest to the free magnetic layers among ferromagnetic layers forming individual fixed magnetic layers, are simultaneously antiparallel to each other. Consequently, the magnetization direction of the free magnetic layer can be aligned in the direction perpendicular to the magnetization directions of these fixed magnetic layers.
The magnetization direction of the free magnetic layer can generally be aligned in one direction by the bias layers. However, the magnetization direction of the free magnetic layer provided between the fixed magnetic layers may be inclined depending on the magnetizations thereof, and as a result, the asymmetry may not be reduced in some cases.
However, according to the spin valve thin-film magnetic device described above, the magnetization direction of the free magnetic layer is unlikely to be influenced by the magnetizations of the fixed magnetic layers, and hence, the asymmetry can be reduced.
In the spin valve thin-film magnetic device of the present invention described above, the direction of a magnetic field moment Hb1 of a ferromagnetic exchange coupling magnetic field formed by ferromagnetic interlayer coupling of the free magnetic layer and a ferromagnetic layer, which is closest to the free magnetic layer among the ferromagnetic layers forming the fixed magnetic layer, and the direction of a magnetic field moment Hb2 of a ferromagnetic exchange coupling magnetic field formed by ferromagnetic interlayer coupling of the free magnetic layer and a ferromagnetic layer, which is closest to the free magnetic layer among the ferromagnetic layers forming the other fixed magnetic layer, are antiparallel to each other in the free magnetic layer.
According to the spin valve thin-film magnetic device described above, since the directions of the magnetic moments Hb1 and Hb2 of the ferromagnetic interlayer coupling magnetic fields formed by the free magnetic layer and the individual ferromagnetic layers, which are closest to the free magnetic layer among the ferromagnetic layers forming the fixed magnetic layer and the other fixed magnetic layer, are antiparallel to each other in the free magnetic layer, the ferromagnetic interlayer coupling magnetic fields counteract each other, and hence, the magnetization direction of the free magnetic layer is not inclined by the ferromagnetic interlayer coupling magnetic fields. As a result, the magnetization direction of the free magnetic layer can be aligned in the direction perpendicular to those of the fixed magnetic layers, and hence, the asymmetry of the spin valve thin-film magnetic device can be reduced.
According to the spin valve thin-film magnetic device of the present invention described above, the direction of a magnetic moment Hd1 of a dipole magnetic field of the fixed magnetic layer and the direction of a magnetic moment Hd2 of a dipole magnetic field of the other fixed magnetic layer is antiparallel to each other in the free magnetic layer.
In the spin valve thin-film magnetic device described above, since the directions of the magnetic moments Hd1 and Hd2 of the dipole magnetic fields of the fixed magnetic layer and the other fixed magnetic layer are antiparallel to each other in the free magnetic layer, the dipole moments of the fixed magnetic layers counteract each other, and the magnetization direction of the free magnetic layer is not inclined by these dipole magnetic fields, whereby the magnetization direction of the free magnetic layer can be aligned in the direction perpendicular to the magnetization directions of the fixed magnetic layers, and hence, the asymmetry of the spin valve thin-film magnetic device can be reduced.
In addition, according to the spin valve thin-film magnetic device of the present invention, when the sensing current flows in the pair of nonmagnetic conductive layers, a magnetic moment Hs of a sensing current magnetic field applied to the free magnetic layer is represented by the formula described below.
Hb1+Hb2+Hd1+Hd2+Hs≅0 
According to the spin valve thin-film magnetic device described above, since the sum of the magnetic moments Hb1 and Hb2 of the ferromagnetic interlayer coupling magnetic fields applied to the free magnetic layer, the magnetic moments Hd1 and Hd2 of the dipole magnetic fields, and the magnetic moment Hs of the sensing current magnetic field is zero, the magnetization direction of the free magnetic layer is not inclined by these magnetic moments, and the asymmetry of the spin valve thin-film magnetic device can be zero.
In the spin valve thin-film magnetic device according to the present invention, it is preferable that the L be 1, the M be 1, and the other fixed magnetic layer be a single ferromagnetic layer.
In addition, in the spin valve thin-film magnetic device according to the present invention, the L may be 1, the M may be 1, and the N may be 1.
When the spin valve thin-film magnetic device is formed as described above, the thicknesses of the free magnetic layer and the fixed magnetic layers are decreased, and shunting of the sensing current can be prevented, whereby the rate of change in magnetoresistance can be increased.
In the spin valve thin-film magnetic device according to the present invention, when sensing current flows, the direction of the sensing current magnetic field applied to the fixed magnetic layer and the magnetization direction of the entire fixed magnetic layer are in the same direction, and the direction of the sensing current magnetic field applied to the other fixed magnetic layer and the magnetization direction of the entire other fixed magnetic layer are in the same direction.
According to the spin valve thin-film magnetic device described above, since the directions of the sensing current magnetic fields, which are generated when the sensing current flows in each nonmagnetic conductive layer, are in the same directions as the magnetization directions of the corresponding fixed magnetic layers, the magnetizations of the fixed magnetic layers are not counteracted by the sensing current magnetic fields, and the magnetizations of the fixed magnetic layers can be reliably fixed, whereby the asymmetry of the spin valve thin-film magnetic device can be reduced.
The thin-film magnetic head of the present invention is capable of reading magnetically written information, which comprises one of the spin valve thin-film magnetic devices described above.
In addition, the floating type magnetic head of the present invention comprises a slider and the thin-film magnetic head described above provided in the slider.
Since the thin-film magnetic head and the floating type magnetic head comprise the spin valve thin-film magnetic devices described above in which the asymmetry thereof is reduced, the symmetry of wave shapes for reading is superior, and the rate of occurrence of errors in reading can be reduced.
A method for manufacturing a spin valve thin-film magnetic device according to the present invention, comprises the steps of forming an antiferromagnetic layer, a fixed magnetic layer composed of at least 2M ferromagnetic layers with a nonmagnetic layer provided therebetween, in which the M is an integer of 1 or more, a nonmagnetic conductive layer, a free magnetic layer composed of at least 2L ferromagnetic layers with a nonmagnetic interlayer provided therebetween, in which the L is an integer of 1 or more, the other nonmagnetic conductive layer, the other fixed magnetic layer composed of one of a single ferromagnetic layer and at least 2N+1 ferromagnetic layers with a nonmagnetic layer provided therebetween, in which the N is an integer of 1 or more, and the other antiferromagnetic layer so as to form a laminate; and performing a heat treatment for the laminate, while an external magnetic field is applied to the laminate so as to align magnetization directions of all ferromagnetic layers forming the fixed magnetic layer and the other fixed magnetic layer in the same direction, whereby exchange coupling magnetic fields appear between the antiferromagnetic layer and the fixed magnetic layer and between the other antiferromagnetic layer and the other fixed magnetic layer.
In addition, the external magnetic field is preferably 4.0xc3x97105 A/m or more.
According to the method for manufacturing a spin valve thin-film magnetic device, by the step of forming the laminate composed of the free magnetic layer, the fixed magnetic layers, the nonmagnetic conductive layers, and the antiferromagnetic layers, as described above, followed by the step of performing the heat treatment while the external magnetic field is applied which is sufficient so as to align the magnetization directions of all ferromagnetic layers forming the fixed magnetic layers in the same direction, a spin valve thin-film magnetic device as described above can be easily manufactured.